In a printing device including a liquid discharge head driven by a voltage waveform input thereto, a change in head temperature due to, for example, the drive history of the liquid discharge head causes a change in the amount of discharged liquid and fluctuation of the print density, even if the same voltage waveform is input. It is therefore desirable that the voltage value of the voltage waveform to be input (i.e., drive voltage) is appropriately adjusted in accordance with the change of the head temperature. If the drive voltage is adjusted during printing on a recording medium, however, the print density changes during the printing, and thus the image quality is deteriorated. In view of this, an image forming apparatus has been known which constantly detects the temperature of a recording head, and changes the drive voltage of the recording head on the basis of the detected head temperature while a recording area of the recording head is facing a medium gap between recording media.
In the above-described image forming apparatus, the temperature of the recording head is constantly detected, and the drive voltage to be input to the head is adjusted on the basis of the latest one of the detected head temperatures during a short time in which the recording area of the recording head is facing the medium gap between recording media.